The root part of Paeonia lactiflora Pall. (Ranunculaceae), commonly known as peony, is a commonly used Chinese herb for the treatment of depression-like disorders. Previous studies in our laboratory have demonstrated that total glycosides of peony (TGP) produced antidepressant-like action in various mouse models of behavioral despair. The present study aimed to examine whether TGP could affect the chronic unpredictable mild stress (CUMS)-induced depression in mice. The mechanism(s) underlying the antidepressant-like action was investigated by measuring serum corticosterone level, glucocorticoid receptor (GR) and brain-derived neurotrophic factor (BDNF) mRNA levels in brain tissues. CUMS, being lasted for 6 weeks, caused depression-like behavior in mice, as indicated by the significant decrease in sucrose consumption and increase in immobility time in the forced swim test. Whereas serum corticosterone level was significantly increased in mice exposed to CUMS, expressions of GR mRNA in hippocampus, and BDNF mRNA in hippocampus and frontal cortex, were decreased in CUMS-treated mice. Daily intragastric administration of TGP (80 or 160 mg/kg/day) during the six weeks of CUMS significantly suppressed behavioral and biochemical changes induced by CUMS. The results suggest that the antidepressant-like action of TPG is likely mediated by modulating the function of hypothalamic-pituitary-adrenal axis and increasing the expression of BDNF in brain tissues.